The study involved 128,000 New York City public school children and included a sizable number of kids from disadvantaged families. But the authors said similar results likely would be found in other children, too.
Of the children born at 37 weeks, 2.3 percent had severely poor reading skills and 1.1 percent had at least moderate problems in math. That compares to 1.8 percent and 0.9 percent for the children born at 41 weeks.
Children born at 38 weeks faced only slightly lower risks than those born at 37 weeks.
Compared with 41-weekers, children born at 37 weeks faced a 33 percent increased chance of having severe reading difficulty in third grade, and a 19 percent greater chance of having moderate problems in math.
"These outcomes are critical and predict future academic achievement," said Naomi Breslau, a Michigan State University professor and sociologist. Her own research has linked lower IQs in 6-year-olds born weighing the same as the average birth weights at 37 and 38 weeks' gestation, compared with those born heavier.
Image: Girl in school, via Shutterstock.